Electron tube circuit means responsive to a signal pulse of short duration



Aug. 12, 1952 P. N. MARTIN 2,607,022 ELECTRON TUBE CIRCUIT MEANS RESPONSIVE TO A SIGNAL PULSE -'OF SHORT DURATION Filed April 11, 1950 INVENTOR.

Pal: Martin BY ZQXW 1115' A T TORNE Y Patented Aug. 12, 1952 URAT NQIRK I Y ELECTRON TUBE CIRCUIT MEANS RESPON- SIVE 'TO IA SIGNAL PULSE OF SHORT TownshipyAlleg h eny Countyg Ba assignor to Westinghouse Air i l Application A My invention relates to electrontubecircuit means responsivetoa signal pulseoi short duration, and more particularly to. electron tube. circuit meansfor operating a signaling circuit for a predetermined minimum. time. interval in. response to an input signal which may. be a pulse of very short duration. .7

The present invention is an improvement upon the electron, tube circuit. means; described and claimed-in the copending applicationforrLetters Patent of the United States, Serial No. 155,248, filed April 11, 1950, by William Bruce Coughlin for: Electron Tube CircuitsResponsive to a Signal Pulse of Short Duratiomthe two; applications be-. ingvof common ownership. 1 i- .IIt is well known that x electron." discharge. .devices of the gas filled variety; have the inherent property of becoming conductive or of being fired due; to the ionization of the gas. In order to deionize the gas so-as'to stop .theconduction of. the device, it is necessary to reduce thepositiveanode potential of the devicebelow a certain value for riety.

aashort period of.itime. For example; in'grid-m controlled gas tubes such asthyratrons thecontrol grid is capableot preventing the tube from firing; however, after theltube has. fired" it is necessary to reduce the. positive'anode. potential inorder to stopithe conduction of the tubes.

When the anodeeofan electron dischargede- .vice of the gas filledvariety. is supplied with direct current? energy thecusualmannerzof deionizing; the gas and stopping "the conduction'oi the device.is-to remove the energy-supplied to the anodel l It is a well known expedient to supply the anode of electron discharge devices of=the gas filled variety with alternating current. When this is done the device can fire only on the alternate erate a signaling circuit inrresponse twandduring; an input signal of 1 an extended. duration. Furthermore: the circuit. means should be {Ca-r pableof ;recurrently. responding to successive-input signals. Amuse for. -;such a; circuit means is shown. 'inqthe :icopending application; for; Letters Patent onthe United :states; Serial NO'.J1055144;

Brake Company's. corporation of Ifnnsyl I n 11, 1950, Serial No. 155.254 12 claims. (01. 315-5173) for Vehicle Reporting Systems, filed July 16, 1949, by Richard W. Treharne, Jr. 'In the above referred to applicationthere is shown the apparatus for detecting thepassage of a vehicle such as a train by a certain-point.,; Thepassing train causes the apparatus to produce s, signal or pulse of very short duration such as approximately one millisecond ii the train is traveling at a high rate of speed. However, ifthe train should stop at or be moving very slowly by the detection point, the apparatus produces a signal of extended duration.

It is an object of my invention to Provide an improved circuit means which includes an electrondischarge device of the gas filled variety and wherewith a. signal of a predetermined duration is effected in response to a si naling impulse of very shortduration. i j.

It is a further object of my invention to provide novel andimproved circuits for deionizing an'electron discharge device of the gas filled va- Another object of my invention is the provision of circuit means for an electron discharge device of the gas filled variety incorporating novel means to maintain a signal circuit operated when thetube is recurrently ionized and deionized in response to an inputsignal of some duration.

It is another object of my invention to pro vide an improved circuit means for operating a signaling circuit fora predetermined minimum time interval in response to an input signal pro duced by the apparatus used in the above referred to Vehicle Reporting System.

Other objects of my invention and features of novelty therein will be apparent from the following description taken in connection with the accompanying drawing, 7 l

In practicing my invention} provide an electron discharge device of the gas filled variety such as a thyratron tube having an anode, a cathode, and a control electrode. The tube is provided with an anode circuit which includes in series a timing resistor and the winding of acontrol relay. The anode circuit is normally supplied with energy from a direct current source by a circuit including j a. back contact .of the relay,

and when-the control relay is picked up, the anode circuit is supplied with energyrrorn an alternating current source by a circuit including a front, contaotof the relay. The voltage of both the direct currentsource and the. alternating current source are preferably-"high; enough .to render the tube conductive; however the con trol electrode normally biased in a; negative tive terminal of the source of direct current by a circuit that may be traced from the anode, through the winding of relay CR, through the timing resistor RI, and over back contact b of relay OR to the positive terminaliofbattery KB. The cathode :2 of tube-W'T 'is connected to the negative terminal of battery HB- by a common ground connection as indicated on the drawing.

normally charged to the potential I01 the direct current source. Thus, when "the control relay flows through the anode circuit duets theipartia-l discharging of the capacitor-'and thereby causes the relay to continue to pick upandiplose its front contacts. When the'control-relay closes its front contacts, the alternating current source supplies energy to the anode circuit so thatdurg in picking up opens its back contacts'a current to terminal 8'of-capacitor C'I.

CapacitorCl .is charged to a potential equal to that of the direct current source HB by a circuit that maybetracedifrom terminal I of capacitor Cl, over back contact I) of relay CR to the posi- 1 tiv e terminal bf battery HB and from the negative -termi nal 'ofbattery HB by means of the common ground connections through resistor R2 The resistance of resistor Bil/is -proportioned and arranged so as ing the negative half cycles of the alternating current'the tube becomes deionized and thereby permits the control electrode to regain control of the conductionfthrough the tube. -Alsofwhen the contrdlrelay closes fits 'i-ront contacts, the partially discharged 1 capacitor {is connected in multiple with-the control relay and timing resistor by 'a circuit whichiricludes one-of the front contactsof thecontrolrelay The capacitor then charging capacitor GI to a. suitable value.

order to vsimplify the drawing, the circuit for c discharges caus'i-n'g a current to fiow'through the relay and thetiming gresistor so that the relay remains m the picked up position for a *short period of time, for example, *one second. Thus, if the signal applied to the control electrode is a pulseof short duration, the relay is' picked up for approximately one second, and if the signal is of extended durationthe pulsating current through the control r-elay-willpause the relay to remain-picked up; U-nde-r either condition, the

relay is picked up for at least approximately one second after which time the-relayreturns to its normal position and may be operated again in 'a similar manner. ltycan readilyfbe seenthat the device which isi to} be operated by this c'ircuit means can be governed over the contactsof thecontrol relay.

I shall describe one form of circuit means for operating a signaling circuitfor -a predetermined mini-mum time intervalfinresponse i to an input signal which maybe a pulse of=very shortduration, which circuit means c'ompr'ises a preferred embodiment of thy-invention and is' ad apted for "usewithavehicledetection system! 'Ishall then point; out the novel 'iea'turesjthereoi in claims.

to limit the value of the initial surge of current In supplying energy to the heater 3-...cr tube VT is not shown; :The.rcontrolfielectrodeiior id 1 ef tube VT. isbiased negatively ibya source n'fidirect current that-is applied overra (circuit that may be traced from the .grid: I, through :resistor IRG- to the negative terminal ofcbattery GB, and from the positive terminal of batteryGB to. the cathode. 2 of tube VI... :The partsare farrangedrand proportioned so that the. negative potential applied to lthesgrid iwith respect; tozthescathpde. 2 sufiiciently biasesltubeVT to'ther'eby prevent vthe firing of, or conduction through tubev VT even though the proper positiveuoperatingpotential .is applied to'theranodec i with respectsto. the cathode 2. It is to be understood :that..:other:well known means for :bias'ingrthtrratron :tubes maybe used and that myi invention :is:not limitedto the method herein shown... 33:1 7 The input signalzsource, mtshown; which 'produces theiinput signal that icauses 13119 :circuit to operate .connectedto terminals 9 and =11); which are respectively showniconnectedvto, the :grid- 1 of tubeiVT andxto theicathodeilby means .ofr the common ground connections aszindicated.

I 'It'lis well"kno.wn in the art that with a'thyratron tube," even though a large positivepotent-ial is appliegd'to thezanode with respect to the-cathode ifthe potential'with :respelctzto the cathode applied torthe control electroderor. grid isymore negative thanja certain/value, depending :upon

, themagnitude ..of the anode potential, the tube The" accompanying drawing' isa diagrammatic view showing a preferred embodiment of-my in vention. 1 Y I V Referring to the drawing, the apparatus here shown comprises a thyratron tube VT having a control electrode or grid I, a cathode 2, a'heater 3 and an anode 4. The apparatus also includes a control relay CR, a first resistor RI; a second resistorR2; a capacitor G1; a high voltage direct current source HB; a suitable source of alter-nating current energy not shown connected to terminals 5 and B, which provides 'the'proper voltage for operating the apparatus; a resistor RG and a battery GB for applyingfa direct current bias voltage between the grid I and the cathode 2 of tion; that is, the input signal sourceis inactive,-

thyratron tube VT is non-conducting, and the control irelayl CR is in itsdeenergized position.

The anode 4 oftubeVT is connected to theposi is considered :to:.:bev nonedonductive by wirtue, of the factithat the "gas therein is not: ionized. However, when the potential applied to theg-rid is. less negative than. this certain ,valueqthe. tube is said to be .fired.orirenderedyeonductive that ionization of the gas therein'rtakesfplace.

From'the foregoing, itiwill .berseen' that when therinput signalsource is made active and the input signal suppliedirom .theiinput signal source overcomes the negative sgrid zbiasxyoltage applied connections. The partslar'e arranged'and pro 7 portionedflso that the anode current which flows through the 'windinggofi relay CR. energizes, :the relay causing it. to pickup its contacts.

' voltage applied to or when fclaLyCRfflcksupTlts contactspthe p viously. traced :circuit" established over its. :back contact b is. opened. ands-thus. theanode current supplied by battery HB isinterruptedi; "However, anodecurrent.:.will ifiowithrough a ..circuit;.thai may be traced: from terminal 1 of..;capacit0.r. .Cl, resistor Rl,- relay CR, the tube space from the anode]. to the cathode-2 of tubeVT, the common groundconnections, and-resistoriRl toterminal 8. of capacitor Cl-.': Thevcapacitance or capacitor Cl andthe value of the circuit resistance-091111 prising the sum of the resistances of resistors BA 7 current source, over front contact. bot relay,

through s orR he; wind a t i relet htw the anode 4 of tube .V'llandirom the cathpde toterminal 6 or the alternating current source by means V of their common ground connections. Also when relay CR. picks up its contacts and front contact a is closed, a capacitor discharging circuit is completed which may be V traced irom' terminal 1 of capacitor CI thrcugh resistor Rl, through the winding of relay CR, and-over front contact a of relay CR to terminal 8 of capacitor CI. It will also be noted that resistor R2 is connected in multiple with the anode 4 and cathode 2 of tube V'I by a circuit that may be .traced from the anode Lover front contact .aof relay CR, through resistor CR2 and by means of their common ground onnections'tothe cathode Z of l bevrfi us when)? n es? arein theigpicke'd up positions, the. alte ting current sourcefeonnected"between termiriaIsfS I and 6, istconnectedlinf series with the. charged "c'tptct or cl, which is'connected in multiple. with thelcon trol jrelay "ca the resistor at; land? the anodeathode circuit ofitube VTjwhi'ch is con- 'nectedin multiplewith resistor R2; 'j tilt is obvious that} the potential "applied to' the anode 4 withrespect t t e cathode 2 or tube VT by the reviously Itracedcircuitwill be atany V instant the algebraic of the voltage across the capacitor Cl and thevoltage' of the alter .nating currentlsource and obviously'the :potential applidtc thei anode 4 with respect to the cath ode '2 maybeatltims either positive ornegat'ive. Therefore, it fcan be seen that during the" time that the potential. applied to" the anode" [with respect to Ythe cathod'e 2, is negative, thegas within the .tiibe'YT becomes deionized and there isho conductionftl'irough the tube. Also, during the tiin that the potential applied to'the anode .4 with respect to the cathode is positive and greater thanthe ionizing potntialjof thej' tube,

the. gas within the tube VT becomes ionized and there isf'conduction through the tube provided "that the] input signal suppliedlfrom' the input signal source overcomes the negative grid bias 'the tube VT. The currentthat .flows through t previously tracedfcircuitj when there is conduc't n througli'the tube. VT charges capacitor Cl. toIa yoltage that" is somewhat less than the peakl'v oltageof thealternating'current source.

- 6 relay CR, the capacitor-discharges through the series combination. The values of the capacitanceof capacitor C3] and the resistance of the winding of relay ,CR. and resistor RI, are 80 P170- portioned thatthe current thatflows during the dischargingof capacitor Cl sufliciently energizes relay .CRgto cause it to continueto :retain its contacts in their picked up positionfor a desired minimum time interval which may be approximately one secondbefore the current decays to such a low value that the relay releases its contacts. It is obvious that theyalues of these circuit components may be chosen to provide greater or less time delay before the, relay CR releases its;;contacts;:and.;that my; invention is not limitedto the approximately onesecondtime delay asgshownin thisembodiment, i

. Thus, if the inputtsignal which initiated the circuit operation ,describedabove is of extended duration, thecontrol relay CR picks up its contactsand they remain picked up during the time the input signal is applieddn addition to approximately one second immediately followin the, re-

moval of the, input signal depending upon the condition ready to be reactuated,

When ,the inpu signal; which initiates the circuit;0DQration is apulse of very short duration, the circuit operationisas described above except that when the; control relay CB, picks up its contacts thereby closin the circuit over its front contactaht ee s :w thin e V becomes d ionized and the tube will not become conductive because the-negativegrid bias potential applied toitg control electrode on grid I in the absence f uit lew n utsienal. preven s t e ube from fi g o y c m c nduct ve .T us e o e a t i t c nt lre a h v i pi k up. re a nic ed unio ap x ma ely one. se ondd inc, upon. t e. a u s th ircu m on i t e. ca tor: -.d Scha s ne c r ui W en th control relay. CR re1eases its contacts, the appathe drawing. It iS lJQbB'; understood, however,

that, thaarrapg'ement-of-the contacts of relay CR for controlling particular circuits is not limited to that shown on the, drawing but that other contact arrangements may be provided if desired; Althoughamy invention isiespecially suited fcr use inconne'ction with vehicle detection systems,

itsliould be pointed out that my invention is not limited tosuch' use, but that it may be used in other applications where a short input signal or pulse is to be used for operating another circuit for a considerable longer period of time.

- AlthoughI have hereinshown and described only one form "of apparatus embodying my invention, it "is to be 'under'st'ood "that various c n e an 'mqd a en m be m therei gi'zedposition, ia cap'acitorymeans governed by said relay "inits deenergized position Jfor charging said capacitor from said direct current source,

. Sam capacitor throughisaid WindmgoiJtheiccinmeans including saidszcnargedcapacitor for sup- 7 plying. currentto said circuit from said charged capacitor during thetime thatsaid relay 'is operated from its deenergized to' itsenergized 'posimen, and means governed by said relay inits energized position fordischarging said capacitor through said winding of' the control relay, the

parts being so proportionedlthat said relay -will be operated to its energized position in response to a predetermined condition of said control electrode. V i

2. In combinationfasource ofdirect current, a source of alternatingwcurrent, agas-filled electrondischarge device'having an anodaacathode and a controlelectrode, acontrol relay, a circuit connected across said anode and cathode and including a winding of said relay, means gov-V erned by said relay in its deenergized position 7 for supplying direct current to said circuit from said direct current source, means governed by said relay in its energized position'for supplying alternating current to saidcircuit from said'alternating current source, a capacitor, means governed by said relay in its deenergized position for charging said capacitor from said direct current source, means including said' chargedca-' pacitor for supplying currenttosaid circuit -from said charged capacitor during the time that said V relay is operated from its deene'rgized'to its enertrol relayi'and a source of bias-voltage connected across said control :Jelec'trode sand cathode: Land so proportioned to :nermaiiy render said direct current "source" magsam :alternating acurrent source inefiective to fire :said dischargeudevice, a source-of inputsignal voltage connected across said -control= electrode and cathode,;iand .said source of" input signal voltage being effective at times to' render said direct current source and said alternating current source effectivefto: fire said discharge-device v 1 1::

'4. In combination; a source of direct current, a source oi alternating current, agas-ifill'ed telectrondischarge device having an-anode,:a cathode and'a control electrode; a coritrolrelaypa circuit connected across said anode and cathodeand including a winding of said relay, said relayqhav ing contacts operable from ,a first' to a'fsecond position ;-when'- its winding is energized, means including one of said contacts "of the control relay inf its -first position ior supplying' direct current to said circuit from said direct current 7 source, means "including one of saijd contacts 'o'f the 'controlrelay in itssecond position ion 'supplying-alternating current to said circuit from said alternating current source, a capacitor,

means including one of said contacts of the control relay in its first position for charging sa'id capacitor from said direct current source, means including said charged capacitor for supplying current to jsaid'anode circuit from said charged capacitor during the time that said contacts of the control relay are moving between their first and second positions, and means including one of said contactsfof the control relayin its second position for-discharging said capacitor through said winding of the control-relay; thel-partsibeing so proportioned that said relay willbe operated to its energized position in response/to; a pr-e determined condition 'of said corrtrol ele'ctrode'.

gizedposition, means governed by said relayin its energized position for discharging said capacitor through said winding of the control relay, a source of input signalvoltage, and means to connect said 1 input-signal voltage source across said controllectrode and cathode, said source of input signal voltage being efiective at times to render said direct current source "and said alternating current source effective to fire said discharge device. a 7 i 3. In combination, a source of directcurren-t, a source ofalternating'icurrent, a-gas-filled electron discharge 'devicelhaving an anode, a cathode and acontrol'electrode,.a icontrolrelay, a circuit connected across .said anode and a cathode and including a; winding of said relay, means governed by said relay in its deenergized position for supplying direct current to said circuit from said direct current source, means governed by said relay in its energized position for supplying alternating currentzto said circuit from said alternatingcurrent source, agcapacitor, means governed by said ,relay initsdeenergized positionrfor charging said capacitor from said direct current source, ,means'including said charged capacitor for supplying current to 'said circuit from said charged'jcapacitor during the time that 'said relay is operated from its deenergized to'its energized position, means governed "by said relay in its energized position for discharging 5., In' combination, a source of" direct "current, asource of alternating current,;a thyra'tron tube having an anode, a cathode and-a -control elec trode, a control relay, "2; circuit 1 connected'across said anode, and cathode "and including a wind ing of said i-e'lay; said rela having contacts operable from a .first'to a second position when its winding is energized, meansincluding one of said contacts of the control relay in its first position for supplying direct current to said circuit from said directcurrentsource, means in.-

V eluding one of saidcontacts of the controlirelay in its se'cpndiposition for "supplying alternating current to said circuit from said alternating current source, a capacitor,-means including one offisa'i'dcontacts ofthe control relay in its first position for charging said capacitor from said directficurrent source, means including said charged capacitor for supplying current :to said anode circuit from 'said charged capacitor during thetiine'that said contacts ofthe control relay are movingbetween their first and second positions, means including one of said contacts ofj'the control'relay' injits second position for discharging said capacitorthrough said winding of ,the control relay, and'a sourceof bias voltage connected acrosssaid control electrode and cathodeand soproportioned to normally rendersaid direct current sourcean'd said alternating current source ineffective to fire said discharge device. i h I f i .f;[n :combination,1a"first pair; of terminals adapted (to jbefconnected to; a sourcef of ganect current, "a second pair oftrminaIS adaptec'i'to trol relay, the'p Y 7 when said terminals are connectedto said sources be connected to aisourcer of i alternating current,

a gas-filled electron discharge device "having an anode, a cathodeand a control electrode, a control relay,:a circuit'c'onnected across said anode and cathode and including a winding of said relay, means for cbnnecting said circuit to said first pair 'of 'terminals' when said relayjis in its deenergized "position, means for connecting said circuit to'said second'pa'ir of terminals when said relay is in its energized' -posltionj a capacitor, means governed by said relay 'inits deenergized position for connecting said capacitor to'said first pair of terminals, circuit means for connecting sald capaci'tor tobsaid circuit du'ring'the time"- o1 current saidu-elay 'willbe operated to its ener gized position in response to a predetermined condition"ofsai'deontrol eleetrode'.- I

, '7..In' 'combination ,j a fir'stfpair of iterrninals adapted some connected 'to-"a soiirce of direct be" 'onnected'to a source 'ofa'lternating current,

said direct current source andsaid' alternating current source ineffective to fire said discharge current, alsecond painof ter'rninal's adapted to a gas-filled electron discharge device having an anode ya' cathodeand control electrode, a control-relay; athcuit connected across said to a source of input signal voltage and connected anode andcathodean'dincluding aiwinding oi I said relay, mews: governed" by said relay in its device, and said source of input signal voltage 'will be efiective at times to render said direct current source and said alternating current source effective to fire said discharge device.

9. In combination, a first pairof' terminals adapted to be connected to a source of direct current, a second pair of terminals adapted to be'connected to a source of alternating current,

a gas-filled electron discharge device having an anode, a cathode and a control electrode, a control relay, a circuit connected across said anode and cathode and including a winding of said relay, said relay .having contacts operable from afirst to a second position when its winding is energized, means including one of said contacts of the control relay inits first position for connecting said first pair of terminals to said anode circuit,'means including one of said contacts of the control relay in its second position for connecting said second pair of terminals to said anode circuit, a capacitor, means including one 'of said contacts of the :control relay in its,

first position'for connecting said capacitorto said firstpair of terminals-circuit means for connecting said capacitorto said anode circuit during the time that said contacts of the control-relay are moving between their first and second positions, and means including one of said contacts of the control relay in its second position; for connecting said capacitor to said winding of the control relay, the parts being so proportioned that whensaid terminals are connected to said sources of current said relay will be operated .toits energized position in response across said control"ele1ctrode-:and cathode, the

parts being so proportioned that when said terminals are connected tor-said sources of current and voltage, said source of input signal voltage will be effective at times to render said direct-currentls ource and said alternating current source eflective to fire said discharge device.

8. In combination, a first pair of terminals adapted to be connected to a source of direct current, a second pair of terminals adapted to be connected to a source of alternating current, a gas-filledelectron discharge device having an anode, a cathode and a control electrode, a control relay, a circuit connected across said anode and cathode and including a winding of said relay, means governed by said relay in its deenergized position for connecting said circuit to 1' to gampredetermined condition of said control 10. In combination, a firstpair of terminals adapted to .beconnected to a source of direct current, -a: second pair, of terminals adapted'to be connected 'to a source of alternating current, a thyratron tube having an anode, a cathode and a control electrode, a control relay, a circuit connected across said anode and cathode and including a winding of said relay, said relay having contacts operable from a first to a second position when its winding is energized, means including one of said contacts of the control relay in its first position for connecting said first pair of terminals to said anode circuit, means including one of said contacts of the controljrelay in its second position for connecting said second pair of terminals to said anode circuit, a capacitor, means including one of said contacts of the control relay in its first position for connecting said capacitor to said first pair of terminals, circuit means for connecting said capacitor to said anode circuit during the time that said contacts of the control relay are moving between their first and second positions, and means including one of said contacts of the control relay in its second position for connecting said capacitor to said winding of the control relay, a third pair of terminals adapted to be I1? connected to a source of bias; voltage and connected across said control electrodeandcathode,

' a fourth pair of terminals adaptedrto be connected to a source of input signal voltage and connected 'across said control electrode and cathode, the parts being so proportioned that when said terminals are connected to said sources of current and voltage, said source of bias voltage willanormally render said direct contact of, said relay and said direct current 7 source, a second anode .circuitconnected across said anode and cathode; and including said winding' and a front contact. of said;relay and said alternating currentsource, a source of? input signal voltage, an input circuit" connected across said control electrode and cathode and including said source of signal voltage,. said input signal voltage source poled to rendersaid direct current source and said alternatingcurrent'source effectiveto fire said: discharge device, a capacitor, a firstcircuit: meansincluding a back contact of said. relay connecting said capacitor to said direct current source to charge thecapacitor, a second circuit meansqconnecting said capacitor across said relay winding; to energize the relay by the discharge of said capacitor when the back contacts of therelay are opened; said capacitor by its discharge, effective to pick up the relay and retain the. relay picked up :for a selected time interval, whereby the relay is-picked up and retained. picked uprorisaid selected time interval, i

in response .to: alrelatively short pulse of signal voltage, is retainedpicked up as long as'the signal voltage continues and is released whenthe signal,

voltage'ceases, and a signalcontrol circuit in-' cluding a contact of said control relay.

12. Incombination, a first pair of terminals to which a source of direct current maybe connectedya second pair of terminals to which a 12 source of alternatingicu-rrentnmayibe connected, a third pair :of. terminalsitdwvhichaasourceot bias voltage may: be; connected; a. fourth: paimof E'ter-,: minals to'whichxa source ofsinputisignalvoltage may berconnectemraga'sifilled electron discharge device having anianodeig aqcathode andza control electrode: afcontrol relay having ai'winding and front 1 and. back c0ntacts;, a -firstranodei circuit connected across said; anodezrand 'cathodei'and including; said: windingjand a: back contact? of said. relay and saidxfirst pair cffterminals; asecei ond anode; circuit 1 connected across: said'xanode and cathode and; including; said windingpand 1a front contact of said relay and said second pair of terminals, a1 first 'npui; circuit connectedacrosssaid: control; electrode and cathode" and including said: third pair pffiterminalspa second input: bi'lr; cuit connectedtacross said contrel eleetrode and. ath de an lgd iea eidr rt ir; e ei l i wi l r t=:a incutvcircui sroled for. said discharge, deviceto be-;normall-y;- non-,-- conductive-due to abias voltage at said thirdzpair of terminals andlfor the-= discharge deviceto be fired due'to a signal-voltage at saidfourth pair of terminals, a capacitor, afirst circuit means including aback contact of said relay connecting, said-capacitor. acrosssaid first pair ofterminals for charging; the capacitor, 2, secondycircuit, means connecting said capacitor across said Winding. of. said relay for supplying current to the Winding due, to the dischargeof the capacitor when:the back contacts of saidrelay are-opened, said capacitor by its discharge through said second circuit means: effectiveto pick up said relay and to retain itpicked up for aselected timeinterval in response to the ,firing, of the discharge device due toa short pulse-of signal voltage at said fourth pair of terminals, said. second anode circuit. effective to fire the discharge device and retain the relay picked up inresponse to a prolonged signal voltage at; said fourth pair of terminals and-to deionize said device whena signal voltage ceases, and a. signal control circuit including a. contact of: said'relay. i PAUL N, MARTIN,

f RE ERENCES. CITED l file of: this patent; v

UNITED S TATESPATENTS' Number Name Date.

1,977,256 Swart Oct. 16, 1934 'Ihefollowing references. are oi-record in the 

